The development of remote radio unit concepts requires at least two parallel aligned printed circuit boards (PCB) mounted on one common heat sink. Usually, certain components are mounted e.g. by soldering to both PCBs. These components must be shielded from other areas of the PCBs due to EMC (Electromagnetic Compatibility) radiation. This may be done by using a traditional cover with walls separating PCB areas from each other. However, because of mechanical tolerances when attaching the PCBs to the common heat sink, a gap between the board edges may not be avoided. Thus, using a single cover crossing the gap may result in EMC leakage under the cover through the gap. Therefore, according to some solutions, two separate EMC shielding covers may be used, which, however, does not allow for components to cross between two PCBs. Another solution is to use one single cover for both PCBs and have one single shielding cavity wall on each side of the board edges. This results in a double wall which may reduce the available PCB area and complicate connecting components to both PCBs.